Cold transporting device

ABSTRACT

An apparatus and method of transporting cold from a source of cold to an object to be cooled, with a quantity of cold stored in a regenerator, which cold can subsequently be used during cooling the object in addition to the cold from the cold source, thereby temporarily providing a greater cooling capacity than can be supplied by the cold source alone.

United States Patent Jan Mulder Emmasingel, Eindhoven, Netherlands 48,794

May 18, 1970 Dec. 28, 1971 Continuation of application Ser. No. 830,440, Apr. 30, 1969. This application May 18, 1970, Ser. No. 48,794

Inventor Appl. No. Filed Patented COLD TRANSPORTING DEVICE 12 Claims, 3 Drawing Figs.

US. Cl 62/99, 62/118, 62/185, 62/201, 62/435, 62/6 Int. Cl F25d 17/02 Field of Search 62/6, 435,

[56] References Cited UNITED STATES PATENTS 1,891,714 12/1932 Jordan 62/201 1,980,688 11/1934 Lewis 62/434 2,512,545 6/1950 Hazard 62/434 3,101,596 8/1963 Rivia 62/6 FOREIGN PATENTS 654,493 12/1937 Germany 62/325 Primary Examiner-William J. Wye Atlorney- Frank R. Trifari ABSTRACT: An apparatus and method of transporting cold from a source of cold to an object to be cooled, with a quantity of cold stored in a regenerator, which cold can subsequently be used during cooling the object in addition to the cold from the cold source, thereby temporarily providing a greater cooling capacity than can be supplied by the cold source alone.

PATENTEB UEB28 lElYl fig.3

INVENTOR.

JAN MULDER CENT COLD TRANSPORTING DEVICE This application is a continuation of Ser. No. 830,440, filed Apr. 30, 1969.

The invention relates to a cold transporting device suitable for being used between a source of cold and a place to be cooled comprising a system of ducts which on the one hand comprises a first heat exchanger for exchanging heat with the source of cold and on the other hand a second heat exchanger for exchanging heat with the place to be cooled, at least one pumping device being arranged in said system of ducts for circulating a transport medium in said system.

A device of the type to which the present invention relates has already been proposed. As a source of cold may be used, for example, a refrigerator, for example, a cold gas refrigerator, while the place to be cooled may be formed, for example, by a cryosurgical instrument, a cryopump or a preparation, for example, a paramagnetic salt for adiabatic demagnetization experiments. Such objects are often used at the low operating temperature only for a short period of time, while between two successive periods of use the object may heat up to a high temperature, for example, room temperature.

In the intermittent use of the apparatus, in which the place to be cooled should be maintained at the desired low operating temperature only for a comparatively short period of time, the demand for cold is consequently also intermittent.

A difficulty in this type of apparatus is that for cooling from room temperature to the desired very low operating temperature a refrigerator is required having a comparatively large cooling capacity. Once the operating temperature of the object to be cooled has been reached, a much smaller cooling capacity is sufficient to maintain said temperature. This consequently means that for normal operation the refrigerator is, as it were, too large which, of course, is unfavorable from an economic point of view. I

it is the object of the invention to provide a solution to this problem and the invention is based on the recognition of the fact to store wholly or partly the cold supplied by the cold source in a store, during the available usually comparatively long period preceding the cooling of the object to be cooled to the desired low operating temperature, which stored cold is then available extra during cooling to bring the object to be cooled rapidly at the desired low operating temperature.

In order to reach the end in view, the cold transporting device according to the present invention is characterized in that the system of ducts of the transport device comprises a first communication duct which communicates at one end with one part of the system of ducts situated between the first and the second heat exchanger, and at the other end communicates with the other part of the system of ducts situated between the first and the second heat exchanger, one or more controllable cocks being present to convey the flow of medium fully or partly through the communication duct, a cold store being furthermore present through which the medium can flow and which is situatedin the communication duct or that part of the system of ducts situated between the connection places of the communication duct and in which part the first heat exchanger is arranged, a bypass being present in the latter case which communicates on either side of the cold store with the system of ducts, one or more controllable cocks being present for conveying the flow of medium fully or partly through said bypass.

In this manner a cold transporting device is obtained in which, by adjusting the said controllable cocks, the flow of transport medium is conducted-in a period preceding the use of the object to be cooled (for example, during a part of the night or when the apparatus to be cooled is made ready for operation)along the source of cold and the cold store, in which period medium does not flow through the second heat exchanger. In this case the cold supplied by the source of cold will be stored in the cold store. During the subsequent use of the object to be cooled the controllable cocks are set so that the medium then flows through the cold store, the first heat exchanger and the second heat exchanger. A comparatively large cooling capacity can now be transported to the second heat exchanger by the flow of medium, so that the object to be cooled will be cooled very rapidly. Remarkable is that in this period more cold per unit of time is supplied to the second heat exchanger then is supplied by the refrigerator. This extra cooling capacity is supplied by the cold store. After the desired low operating temperature has been reached, the cold store is disconnected from the flow of medium, and the medium then flows only through the two heat exchangers. The source of cold is proportioned so that at that instant sufiicient cold is supplied to maintain the reached temperature. In this manner a very rapid cooling of an object to be cooled to the operating temperature can be obtained with a comparatively small source of cold.

The cold store may be, for example, a regenerator, having a large thermal capacity and a good heat transmission between the material and the transport medium. The thermal conductivity in the direction of flow in such a regenerator nonnally is low. It is feasible in circumstances to choose the thermal conductivity in the direction of flow to be high so that no temperature gradient is present any longer across the regenerator.

In a further favorable embodiment of the cold transporting device according to the invention, the transporting medium is helium. This ensures that the cold can be transported in the whole temperature range above 4 K. Especially with pressures in the region between 10 and atm. and at lower temperatures the density and hence the thermal capacity of the helium will be large so that cold can be transported with a good thermal efficiency. When the source of cold supplies its cold at temperatures which lie above the critical temperature of hydrogen, the transport medium In a further favorable embodiment of the cold transport device according to the invention is hydrogen. The advantage of hydrogen as compared with helium is that the diatomic hydrogen has a larger specific heat than the monoatomic helium so that with the same flow of volume and temperature difference a larger quantity of thermal energy can be transported.

In a further favorable embodiment of the cold transporting device according to the invention, only one pumping device is present which, the cold store is being included in one of the parts of the system of ducts situated between the first and the second heat exchanger, is arranged in that part of the system of ducts which comprises the first heat exchanger and lies between the connection place of the communication duct in the other part of the system of ducts situated between the first and the second heat exchanger and the connection place of the bypass in the system of ducts which is situated on the side of the cold store facing the first heat exchanger or in that part of the system of ducts situated between the other connection places of the communication duct and the bypass in said system of ducts. The cold store being incorporated in the communication duct, according to another embodiment, the pump is incorporated in that part of the system of ducts which is situated between the connection places of the communication duct and which part also comprises the first heat exchanger. Such an embodiment provides the advantage that only one pump is sufficient to circulate the medium in the system of ducts, irrespective of the choice of the possible ducts which the transport medium can follow in the system.

In a further favorable embodiment of the cold transporting device according to the invention a second communication duct is present in the system of ducts which communicates with the system of ducts on either side of the first heat exchanger and in which the part of the system on one side of the said connection places comprises only the first heat exchanger and the communication duct comprises a heating device, in which furthermore one or more controllable cocks are provided for conveying the flow of medium fully or partly through the second communication duct. Since the part of the system on one side of the second communication duct comprises only the first heat exchanger, again only one pump is sufi'rcient to circulate the transport medium in the system of ducts.

In practice it is often desirable to heat the object to be cooled, for example, a vacuum plant, again to room temperature after a given period of use, so that the plant can be opened without too much water and CO, condensing on the second heat exchanger. By conveying the flow of medium through the second communication duct and using the heating device provided therein the transport medium can rapidly be heated in a simple manner in which the comparatively warm transport medium can bring the cooled place at the ambient temperature due to heat exchange in the second heat exchanger.

In order that the invention may be readily carried into effect, three embodiments thereof will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:

FIGS. 1, 2 and 3 diagrammatically show three embodiments of cold transporting devices (not to scale) in which a cold store is arranged in said transport devices through which the medium can flow fully or partly.

Reference numeral 1 in FIG. 1 denotes a system of ducts which comprises helium. This system comprises the first heat exchanger 2, a duct 3, a second heat exchanger 4 and a duct 5. The system of ducts further comprises a pump 6 which circulates the helium. The heat exchanger 2 is in heat exchanging relationship with a source of cold 7 shown diagrammatically which may be, for example, a cold gas refrigerator. Furthermore, the second heat exchanger 4 is in heat exchanging relationship with an object 8 to be cooled which may be, for example, a vacuum plant. In the duct 3 a regenerator 9 is provided in which a bypass 10 is arranged across said regenerator. This bypass l communicates on one side of the regenerator at 11 with the duct 3 and on the other side also with the duct 3 through a control slide 12. The cold transporting system shown in FIG. 1 furthermore comprises a first communication duct 13 which communicates on one side, through a control slide 14, with the duct 3, while said communication duct communicates with its other side at 15 with the duct 5. A second communication duct 16 is furthermore provided which on one side at 17 communicates with the duct and on the other side communicates with the duct 3, through a control slide 18. In the second communication duct 16 a heating device 19 is incorporated. The operation of this cold transporting system is as follows. Before proceeding to cooling the object 8 to be cooled by means of heat exchanger 4, the regenerator 9 is stored with cold. This occurs by adjusting the control slide 18 so that the communication duct is closed while the control slide 12 closes the bypass l0 and the control slide 14 closes the second heat exchanger 2, The pump 6 will now circulate helium through the regenerator 9, the communication duct 13, the duct 5 and the first heat exchanger 2, where the helium is cooled by the source of cold and is then conducted again by the pump to the regenerator where it delivers its cold to the regenerator material. This is continued until the regenerator 9 is cooled to the lowest temperature which the source of cold can supply. A rapid cooling of the object to be cooled can be obtained by setting the control slide 14 in a position in which the communication duct 13 is closed and leaving the control slides 12 and 18 in their above-described positions. The helium will then be circulated by the pump 6 through the regenerator 9. As a result of the properties of the regenerator, the gas will flow out of the regenerator for a given period of time at a constant low temperature. The medium then flows through the second heat exchanger 4, where it supplies its cold to the object to be cooled and the medium will then flow through the heat exchanger 2, via the duct 5, where it exchanges heat with the source of cold and then it flows again through the regenerator. In this manner a cooling capacity exceeding the capacity supplied by the regenerator is temporarily available. A very rapid cooling of the object 8 to be cooled is thus obtained. After a given period of time the object to be cooled will have reached the operating temperature. At that instant the control slide 12 is set in the positions in which the duct to the regenerator 9 is closed so that the bypass is opened. The medium will then flow through a part of the duct 3 and through the bypass 10 to the second heat exchanger where it exchanges cold with the object to be cooled, after which the helium further through the duct 5 flows to the heat exchanger 2 where the helium exchanges heat with the source of cold 7 and then flows back to the pump 6. At that instant the source of cold 7 will supply sufficient cold to maintain the object 8 to be cooled at its operating temperature. This means that, with a comparatively small source of cold 7 which is large enough for maintaining the normal operating temperature, a very rapid cooling of the object to be cooled can nevertheless be obtained. After a given period of use it is usually desirable, to heat the object to be cooled again to the ambient temperature. This may occur, for example, in vacuum plants in which, before opening the vacuum space, it is desirable that the heat exchanger 4 or the cooling surface communicating therewith is again at room temperature since otherwise a large quantity of water and CO would condense on said cold parts. This heating of the cooled object 8 may be carried out, for example, by stopping the pump 6 and bringing the cooled object at temperature by means of an electric heating device. This often gives extra structural complications. In the cold transporting device shown in FIG. 2 the heating of the object 8 to be cooled may be carried out by setting the slides l8, l2 and 14 as follows: slide 18 is set in the position in which the duct to the first heat exchanger 2 is closed and the communication duct 16 is opened. The slide 12 is set in the position in which the duct to the regenerator 9 is closed and the bypass 10 is opened, while the slide 14 is in its position in which the communication duct 13 is closed. Furthermore the heating device 19 is actuated. The medium now flows from the pump 6, through the bypass 10, the second heat exchanger 4 and the communication duct 16. In the communication duct 16 heat is supplied to the helium by the heating device 19 so that this helium is supplied to the second heat exchanger 4 in a comparatively warm condition, where it supplies its heat to the object to be cooled. Thus heating of the object 8 to be cooled is possible in a simple manner. If desired, heating of the object to be cooled may be carried out somewhat differently. At the time the object was cooled heat was stored in the regenerator. By setting the slide 12 in that position in which the bypass is closed, the helium flows through the regenerator 9 in-which it is heated. This warm helium now flows through the heat exchanger 4, so that the object 8 is heated. At a given instant the slide 12 is set in that position in which the medium can flow through the bypass 10 while at that instant also the heating device 19 is actuatedv so that heating of the object then occurs as described above.

FIG. 2 shows a cold transporting device which in outline corresponds to that of FIG. 1 and in which corresponding components are referred to by the same reference numerals as in FIG. I. The only difference is that the regenerator 9 in this embodiment is placed in the part 5. The operation of the device shown in FIG. 2 in outline corresponds to that of FIG. 1, so that no detailed description need be given. This embodiment, however, may in circumstances provide advantages as compared with the device shown in FIG. 1.

FIG. 3 shows a cold transporting device which also in outline corresponds to that of the preceding Figures and in which therefore corresponding components are referred to by the same reference numerals. The regenerator 9 in this embodiment is accommodated in the first communication duct. The operation of this device is as follows. The control slide 18 is placed in such a position that the communication duct 16 is closed. Furthermore the cock 21 is closed and the cock 22 is opened. The medium will now flow from the pump 6 through the duct 3 to the regenerator 9 and then through the communication duct 13 and heat exchanger 2 again back to the pump. The medium is cooled in heat exchanger 2 and then supplies its cold to the regenerator 9 which consequently is cooled. Upon starting the cooling of the object 8 the cock 21 is partly opened, while the cock 22 is partly closed. The medium from the pump 6 will now flow partly through the regenerator 9 and for the remaining part through the heat exchanger 4. At the two flows are mixed and this results in a mixed temperature of the helium heated in the heat exchanger 4 and the cold medium from the regenerator 9. This medium then flows through the heat exchanger 2 in which it is cooled. In this manner the production of cold of the regenerator 9 is added to that of the refrigerator. Upon reaching the desired operating temperature of the object 8 to be cooled, the cock 22 is fully closed while the cock 21 is fully opened so that the medium then fully flows through the heat exchanger 4 and through the heat exchanger 2, the cooling capacity of the source of cold being sufficient to maintain the reached temperature of the object 8. Heating of the object may again be effected by setting the control slide 18 in that position in which the medium from the pump 6 flows through the cock 21, through the heat exchanger 4 and then through the communication duct 16 with the heating device which is then energized. In this case, heat is supplied to the object to be cooled from the heating device 19, so that heating of said object is obtained in a favorable manner.

It may be obvious from the above that the invention provides an extremely advantageous and simple construction of a cold transporting device, in which a quantity of cold can be stored in a cold store which may be, for example, a regenerator or another heat accumulator, which stored cold can be used during cooling the object to be cooled, so that more cold per unit of time is supplied to said object than can be supplied per unit of time by the refrigerator, so that a shortening of the cooling period is obtained.

What is claimed is:

l. A device for transporting cold via a transporting medium between a source of cold and an object to be cooled comprismg:

a. a first heat exchanger including first inlet and outlet for exchanging heat with the source of cold,

b. a second heat exchanger including second inlet and outlet for exchanging heat with the object to be cooled,

c. a system of ducts interconnecting said heat exchangers with a first duct between the first outlet and second inlet, and a second duct between the second outlet and first inlet,

d. pumping means in the system for circulating the transporting medium therein,

e. a first communication duct having one end connected to the first duct at a first junction and its other end connected to the second duct at a second junction,

f. first adjustable valve means in the first duct for selectively controlling the flow of medium through said first communication duct and the second heat exchanger,

g. regenerator in one of said ducts for receiving medium from one of said heat exchangers,

h. a bypass duct connected in parallel with the regenerator and second adjustable valve means for selectively controlling the flow of medium through said bypass and regenerator.

2. A cold transporting device as defined in claim 1, wherein the transporting medium is helium.

3. A cold transporting device as defined in claim 1, wherein the transporting medium is hydrogen, when the source of cold supplies its cold at a temperature higher than the critical temperature of hydrogen.

4. A device as defined in claim 1 wherein said regenerator and bypass are connected in the first duct between the first outlet and the first junction.

5. A device as defined in claim 1 further comprising a second communication duct having its ends connected respectively at third and fourth junctions adjacent said first outlet and inlet, and a heater associated with said second communication duct.

6. A device as defined in claim 5 further comprising third adjustable valve associated with said second communication duct for selectively controlling the flow of medium through the first heat exchan er and the second communication duct.

7. A device as de med in claim 1 wherein the regenerator and bypass are connected in the second duct between the second junction and the first inlet.

8. A device as defined in claim 1 wherein the regenerator is situated in the first communication duct, and the second heat exchanger selectively functions as the bypass of the regenerator.

9. A method of cooling an object utilizing cold transported from a cold source via a transporting medium, comprising the steps:

a. transferring cold from the cold source to a first heat exchanger,

b. flowing the medium through the first heat exchanger thereby absorbing said cold,

0. flowing the cooled medium from the first exchanger into a regenerator for storing cold therein, and thence flowing the medium back to the first heat exchanger, thus bypassing the object to be cooled,

d. subsequently flowing the medium (i) again through the first heat exchanger for receiving additional cold, (ii) through the regenerator, and (iii) through the second heat exchanger where the cold from the medium is transferred to the object to be cooled, and then (iiii) returning the medium to the first heat exchanger.

10. A method as defined in claim 9 comprising the further steps for heating the object:

a. flowing medium from the second heat exchanger through a heater thereby heating the medium and bypassing the cold source, and

b. flowing the heated medium to the second heat exchanger thereby bypassing the regenerator, and heating said second exchanger.

11. A method as defined in claim 9, wherein the regenerator is cooled to the temperature of the cold source by flowing the medium therethrough.

12. A device for transporting cold via a transporting medium between a source of cold and an object to be cooled comprising:

a. a first heat exchanger including first inlet and outlet for exchanging heat with the source of cold,

b. a second heat exchanger including second inlet and outlet for exchanging heat with the object to be cooled,

c. a system of ducts interconnecting said heat exchangers, with a first duct between the first outlet and second inlet, and a second duct between the second outlet and first inlet,

d. pumping means in the system for circulating the transporting medium therein,

e. a first communication duct having one end connected to the first duct at a first junction and its other end connected to the second duct at a second junction,

f. a regenerator in one of said ducts for receiving medium from one of said heat exchangers, and

g. adjustable valve means for selectively controlling the flow of medium through said second heat exchanger and said regenerator.

52 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No; ,6 ,043 Dated December 28, 1971 Inventor (X) JAN MULDER It is certified that error appears in the above-identified patent I and that said Letters Patent are hereby corrected as shown below:

In the Title: line 7, delete "830,440" and insert .1

Col. 1, line 1, delete "830,440" and insert --820 ,440-- Signed and Sealed this 17th day of O tobe 1972.

' (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. A device for transporting cold via a transporting medium between a source of cold and an object to be cooled comprising: a. A first heat exchanger including first inlet and outlet for exchanging heat with the source of cold, b. a second heat exchanger including second inlet and outlet for exchanging heat with the object to be cooled, c. a system of ducts interconnecting said heat exchangers with a first duct between the first outlet and second inlet, and a second duct between the second outlet and first inlet, d. pumping means in the system for circulating the transporting medium therein, e. a first communication duct having one end connected to the first duct at a first junction and its other end connected to the second duct at a second junction, f. first adjustable valve means in the first duct for selectively controlling the flow of medium through said first communication duct and the second heat exchanger, g. regenerator in one of said ducts for receiving medium from one of said heat exchangers, h. a bypass duct connected in parallel with the regenerator and second adjustable valve means for selectively controlling the flow of medium through said bypass and regenerator.
 2. A cold transporting device as defined in claim 1, wherein the transporting medium is helium.
 3. A cold transporting device as defined in claim 1, wherein the transporting medium is hydrogen, when the source of cold supplies its cold at a temperature higher than the critical temperature of hydrogen.
 4. A device as defined in claim 1 wherein said regenerator and bypass are connected in the first duct between the first outlet and the first junction.
 5. A device as defined in claim 1 further comprising a second communication duct having its ends connected respectively at third and fourth junctions adjacent said first outlet and inlet, and a heater associated with said second communication duct.
 6. A device as defined in claim 5 further comprising third adjustable valve associated with said second communication duct for selectively controlling the flow of medium through the first heat exchanger and the second communication duct.
 7. A device as defined in claim 1 wherein the regenerator and bypass are connected in the second duct between the second junction and the first inlet.
 8. A device as defined in claim 1 wherein the regenerator is situated in the first communication duct, and the second heat exchanger selectively functions as the bypass of the regenerator.
 9. A method of cooling an object utilizing cold transported from a cold source via a transporting medium, comprising the steps: a. transferring cold from the cold source to a first heat exchanger, b. flowing the medium through the first heat exchanger thereby absorbing said cold, c. flowing the cooled medium from the first exchanger into a regenerator for storing cold therein, and thence flowing the medium back to the first heat exchanger, thus bypassing the object to be cooled, d. subsequently flowing the medium (i) again through the first heat exchanger for receiving additional cold, (ii) through the regenerator, and (iii) through the second heat exchanger where the cold from the medium is transferred to the object to be cooled, and then (iiii) returning the medium to the first heat exchanger.
 10. A method as defined in claim 9 comprising the further steps for heating the object: a. flowing medium from the second heat exchanger through a heater thereby heating the medium and bypassing the cold source, and b. flowing the heated medium to the second heat exchanger thereby bypassing the regenerator, and heating said second exchanger.
 11. A method as defined in claim 9, wherein the regenerator is cooled to the temperature of the cold source by flowing the medium therethrough.
 12. A device for transporting cold via a transporting medium between a source of cold and an object to be cooled comprising: a. a first heat exchanger including first inlet and outlet for exchanging heat with the source of cold, b. a second heat exchanger including second inlet and outlet for exchanginG heat with the object to be cooled, c. a system of ducts interconnecting said heat exchangers, with a first duct between the first outlet and second inlet, and a second duct between the second outlet and first inlet, d. pumping means in the system for circulating the transporting medium therein, e. a first communication duct having one end connected to the first duct at a first junction and its other end connected to the second duct at a second junction, f. a regenerator in one of said ducts for receiving medium from one of said heat exchangers, and g. adjustable valve means for selectively controlling the flow of medium through said second heat exchanger and said regenerator. 